Say Goodbye to the Executive Touring Car, Hello to the Turbo V-8 Techno-Wonder

It's a good bet that the average Audi A8/BMW 7 Series/Mercedes S-Class buyer doesn't care much about dynamics beyond being able to merge ahead of freeway traffic while checking stock prices on their smartphones, or whatever the rich do while commuting. For the rest of us enthusiasts who dream of coming up with the kind of sports-celebrity scratch for a car that can carry the family in comfort while carving up on-ramps, there is the S8.

For its first two generations, the S8 was an executive touring car. This one has a different feel. Chassis tuning is more subtle in part because the ordinary A8, with its sport and individual comfort suspension settings, is already pretty competent, and stiffer tuning can only go so far before this big sporting luxury car gets too harsh. Hence, this new Audi S8, which launches next spring in Europe and in late summer or early fall of 2012 in North America, is all about the engine.

Audi shelved the old S8's V-10 for a new, 4.0-liter V-8 rated at 512 horses, peaking at 5800 rpm. Thanks to the twin-scroll turbo, the torque curve is flat from 1700 to 5500 rpm at a healthy 479 lb-ft. The new engine is mated to Audi's eight-speed automatic, a transmission the next S6 and new S7 won't get. As a result, those cars' engines will be tuned about 100 horses lower. Though Audi says the eight-speed won't package with that engine in these cars, it hints at RS6 and RS7 models that will match the S8 in transmission (and thus in horsepower) in the future.

Because it can get such great power and torque numbers, Audi put its efforts into making the V8T (as the badging on the S8's front fenders indicates) as efficient as possible. First, Audi engineers placed the exhaust manifold and turbo intercooler within the 90 degrees of the V for quicker and more efficient engine warm-up. More importantly, the direct injection engine has a cylinder cutoff system with a sleeve that kicks in a zero-lift cam to cut cylinders two, three, five, and eight at light loads. The twin-turbo V-8 can run on just four cylinders at engine speeds up to 3600 rpm and at speeds up to 112 miles per hour. The car also comes with a start/stop system in Europe that the company says will eventually make it to the U.S., though not at launch.

From this, Audi estimates a 23 percent fuel efficiency gain. While that's on the European cycle, apply that number to the 2009 S8, the last such Audi sold in the U.S., and EPA estimated efficiency is 16 mpg city and 23 mpg highway.

The noise, vibration, and harshness characteristics of cylinder shut-off and stop/start understandably concerned Audi, so engineers developed two big technological breakthroughs to mitigate the noise and the secondary vibrations that make their way into the steering wheel and throttle pedal. Two active engine mounts, designed to be much like stereo speakers, use fluid to actuate a permanent magnet that moves a diaphragm and cancels vibration from the shutoff with counter-vibrations of their own. The Audi S8 is in the running to be named the quietest, smoothest car extant. DTR VMS developed (and manufactures) these ingenious active engine mounts for Audi. It's a South Korean company that bought British supplier Avon Automotive, so don't be surprised for these to show up in a future Hyundai Genesis V-8.

Audi also uses a four-microphone active noise cancellation system to counteract the noise of the cylinders shutting down. It is equally effective. In fact, if there's any complaint about the S8's sound, it's simply that the turbo V-8 makes just a muted sound when you're inside the car, and only under acceleration. The sound is more pronounced if you're a pedestrian.One other tasty bit of high tech are the S8's optional ceramic front brakes, which shave 11 pounds off the weight of each front wheel. Audi hasn't decided whether to offer ceramics on U.S. imports, partly because the option could approach the base price of a VW Jetta and partly because ceramic brakes are not linear like steel brakes. A test-drive proved this. There's a lot of play and mush at the top of the pedal, where you expect the binders to effectively shave off speed. Then, when you find yourself stabbing the pedal further to get some results, the brakes really grab. Will American Audi customers put up with that?

I checked Audi's website. The A8L is a longer wheelbased version...making that version as big as American cars of the past...maybe too big for our shrunken tastes, but the regular A8 is nice sized and luxurious...and weighs about the same as the Jeep Wrangler Unlimited according to Audi. This S8 is even more interesting, but somewhat expensive. Nice job, Audi.

The first time I saw those hideous LED eyebrows in my rearview mirror, I assumed they were some sort of gaudy aftermarket bling. Though I must admit that the thought of anyone, even a hardcore ricer, vandalizing a $100k+ car with a string of holiday lights across the headlamps seemed so unrefined as to be improbably ridiculous. ...But apparantly those Vegas-inspired checkmarks truly are Audi's stock daytime running lights! Wow! I guess you don't have to be cheap to be tacky. --Can you also get a rear deck spoiler and a fart-can exhaust as OEM options on the S8? If a manufactuer as sophisticated as Audi thinks that a "hey-look-at-me!" pimped-out approach to lighting is even remotely stlyish or refined, the future of tasteful LED design looks bleak indeed.

When one needs a stately luxury all-weather fast saloon - S8 is the car. Serious car for serious people.M5 is for showing off on dry days. That is why they are so popular with Russians and middle-eastern crowd.

Book marked.. Great review, and the car sounds amazing always love these things. Shoot I love the regular A8, just one of the sexiest cars around, even the old ones. They still look good today. But M/T I'll be watching how you review 'other' cars seeing as you turned any potential negative here into a positive.

Damn that's expensive! The looks seem a little too understated for the car, but I guess as a sleeper this would be pretty cool. I'd be looking at the R8 at these prices, but as a fast Luxury sedan, this looks like it'll fit its role pretty well. The M5's not going to break a sweat over this car, though. Now that I think about it, both the cars use Twin-turbo V8s. Perhaps a pattern?